What isn't clear from the study, however, is whether the sleep issues actually cause obesity, or if something else might explain the association between sleep problems and obesity.

Researchers analyzed data from about 1,900 youngsters in England. The researchers had about 15 years of follow-up on the children. Those who got the least amount of sleep at ages 5 and 6 had between a 60 percent and 100 percent increased risk of being obese at age 15. (For children aged 5 or 6, fewer than 10.5 hours of sleep a night is considered too little, according to the researchers.)

Children who got too little sleep at other ages were not at increased risk for obesity, according to the study.

The researchers also found that one-quarter of the children were at increased risk of obesity due to sleep-related breathing problems such as snoring and sleep apnea. Those with the most severe sleep-related breathing problems were twice as likely to become obese by ages 7, 10 and 15.

The risk was slightly lower in children whose sleep-related breathing problems peaked at ages 5 or 6, but was still 60 percent to 80 percent higher than among those without sleep-related breathing problems.

The researchers didn't look at whether children with both these risk factors had a higher risk of obesity than those with just one of the risk factors.

"In recent years, lack of sleep has become a well-recognized risk for childhood obesity," study author Karen Bonuck, a professor of family and social medicine, and obstetrics, gynecology and women's health at Albert Einstein College of Medicine in New York City, said in a college news release.

"We know that the road to obesity often begins early in life. Our research strengthens the case that insufficient sleep and SDB (sleep-disordered breathing) -- especially when present early in childhood -- increase the risk for becoming obese later in childhood," she added.

"If impaired sleep in childhood is conclusively shown to cause future obesity, it may be vital for parents and physicians to identify sleep problems early, so that corrective action can be taken and obesity prevented. With childhood obesity hovering at 17 percent in the United States, we're hopeful that efforts to address both of these risk factors could have a tremendous public health impact," Bonuck concluded.

A common cause of sleep-related breathing problems in children is enlarged tonsils or adenoids. If these are a problem, they can be removed through surgery. Another possible cause is misalignment of the jaws and teeth. This problem can be treated with a night guard or orthodontics.

Learning good sleep habits can help children get adequate sleep, Bonuck said.

The study was published online Dec. 11 in The Journal of Pediatrics.

More information

The U.S. Centers for Disease Control and Prevention has more about childhood obesity.